A kind of preparation method of calcium gluconate

Abstract

The present application discloses a method for preparing calcium gluconate, which comprises enzymatic hydrolysis of starch into glucose, and then oxidation reaction of glucose and calcium carbonate under the action of polyether defoaming agent, catalase and glucose oxidase. The liquid surface in the oxidation tank is in contact with the gas phase in the tank and the replacement is fast, which accelerates the oxidation of glucose and improves the oxidation reaction process. The reaction process can be made close to theoretical expectations in a shorter time, and the generation of side reaction products is reduced, thereby improving the product yield and purity.

Description

Technical Field

[0001] The present application relates to an organic metal salt, and in particular to a method for preparing calcium gluconate. Background Art

[0002] Calcium gluconate is an organic calcium salt, mainly used as a calcium fortifier and nutrient, buffer, solidifying agent and chelating agent in food.

[0003] At present, the quality purity of calcium gluconate obtained by the enzyme catalysis method is relatively good in the process of calcium gluconate. In its production process, glucose is prepared into an aqueous solution with a concentration of 10-15wt%, and then calcium carbonate, catalase, and glucose oxidase are added. Air is introduced to provide the oxygen required for the reaction. The oxidation reaction is continued at 30-38°C. Glucose is oxidized in the aqueous phase and under the catalysis of the enzyme to obtain gluconic acid, which then reacts with solid calcium carbonate to obtain calcium gluconate.

[0004] The control of the reaction process is to measure whether the material reaction progress has reached the design point through the residual glucose content in the material. However, the compressed air introduced during the reaction and the carbon dioxide released after the calcium carbonate reaction cause a large number of bubbles and liquid foam to be generated in the reaction environment, which hinder the secondary exchange of oxygen between the liquid surface and the gas phase, resulting in the reaction process being unable to approach the optimal state within the time. In addition, extending the actual operation time leads to an increase in side reaction products and aggravated yellowing of the material. Whether increasing the residual glucose content to end the reaction early and reduce side reactions, or extending the reaction time to ensure that the material reaction is completed, the yield of glucose calcium will decrease, the purity of glucose calcium carbonate will decrease, and more raw materials or impurities will be mixed in. Summary of the invention

[0005] In order to improve the yield and purity of calcium gluconate, a preparation method of calcium gluconate is provided.

[0006] The above-mentioned object of the present invention is achieved through the following technical solutions: A method for preparing calcium gluconate comprises the following steps: S1: Starch and water are mixed to prepare starch emulsion, high temperature amylase is added to the starch emulsion after sterilization, and after heating, primary injection liquefaction and secondary injection liquefaction are performed in sequence to obtain liquefied starch liquid; S2: After the liquefied starch solution is cooled, a composite saccharifying enzyme is added to obtain a glucose saccharified solution after enzymolysis and inactivation; S3: filtering and removing salt using ion exchange resin to obtain purified sugar solution; S4: filtering, concentrating and purifying the sugar solution to obtain a concentrated purified sugar solution having a glucose concentration of 40-45 wt %; S5: stirring and mixing the concentrated purified sugar solution and calcium carbonate to obtain a mixed raw material, and putting the mixed raw material into an oxidation tank; S6: Add polyether defoamer, catalase and glucose oxidase to the mixed raw materials and heat to 35-38°C, stir and introduce pure oxygen, maintain the tank pressure at 0.3-04Mpa for oxidation reaction, detect the glucose content during the oxidation reaction, and terminate the reaction when the residual glucose drops below 0.1wt% to obtain a crude product material; the polyether defoamer is used in an amount of 0.02-0.03g / L of the mixed raw materials.

[0007] By adopting the above technical solution, the present application firstly increases the concentration of glucose, a raw material for the oxidation reaction, to 40-45wt%, and uses pure oxygen as the reaction oxygen supply, thereby increasing the oxidation reaction rate with a high concentration of reaction substrate; Furthermore, based on the reaction process of high glucose concentration and pure oxygen as oxygen supply for the reaction, the present application also adds a polyether defoamer to the mixed raw materials. For the high-speed reaction of high glucose concentration and pure oxygen as oxygen supply for the reaction, the polyether defoamer reduces and quickly eliminates the bubbles caused by the gas discharge in the calcium carbonate during the mixing of the raw materials, the decomposition of hydrogen peroxide during the oxidation process, the release of carbon dioxide by the reaction of calcium carbonate and acid, and the introduction of pure oxygen, so as to avoid the accumulation of bubbles on the surface of the liquid phase to hinder the interaction between the liquid phase surface and the gas phase mass transfer in the tank, thereby the high reaction rate of the oxidation reaction with high glucose concentration and pure oxygen as oxygen supply for the reaction is actually exerted, so that the oxidation reaction in the oxidation tank maintains a long-term high reaction rate, and the reaction time is significantly shortened. Compared with the traditional oxidation process, the reaction time required for the preparation method of the present application to reach the same reaction end sugar concentration under the condition of high concentration reaction materials can be shortened by 200%-400%, and the production of side reaction products is reduced, and the yield and purity of calcium gluconate are improved.

[0008] Optionally, the polyether defoaming agent is one or both of polyethylene glycol and polypropylene glycol.

[0009] By adopting the above technical scheme, polyethylene glycol, polypropylene glycol or a mixture of the two is used as a polyether defoaming agent, which has good water solubility, is not easy to hydrolyze during the subsequent production heating process, and a small amount of hydrolysis products will not precipitate during the calcium gluconate crystallization process, so it is beneficial to obtain high-purity calcium gluconate.

[0010] Optionally, the polyether defoamer is prepared by mixing polyethylene glycol and polypropylene glycol in a mass ratio of 1:0.65, and the dosage of the polyether defoamer is 0.025 g / L.

[0011] By adopting the above technical scheme and using the above type and amount of polyether defoamer, the obtained calcium gluconate has a high yield and excellent purity.

[0012] Optionally: a polyether defoamer is first added to the mixed raw materials in S6, and then the temperature is raised to 35-38° C., and then catalase and glucose oxidase are added, and the oxidation reaction time is 4-6 hours.

[0013] By adopting the above technical scheme, after glucose oxidase is added to the mixed raw materials, it will begin to contact and oxidize glucose. The polyether defoamer is first mixed into and evenly dispersed in the mixed raw materials, so that the defoaming effect and anti-foaming effect of the polyether defoamer can be optimized; at the same time, the effective ingredients of catalase and glucose oxidase are polypeptides or proteins, and the polyether defoamer is first mixed into the mixed raw materials to promote the dispersion of catalase and glucose oxidase in the mixed raw materials, thereby accelerating the oxidation of glucose and the reaction process, and the obtained calcium gluconate has better purity and higher yield.

[0014] Optionally, the process also includes S7: heating the crude product material, adding calcium carbonate to adjust the pH value of the liquid to 6.5-7.5, adding perlite powder, and filtering to obtain a crude product filtrate; the amount of perlite powder added in S7 is 0.50-1.50 g / L of the crude product material.

[0015] By adopting the above technical scheme, after adjusting the pH in S7, the crude product material is mixed with solid and fine calcium carbonate particles. When directly filtered, the calcium carbonate particles accumulate into a filter cake or filter layer with high density and easy to harden, which slows the filtration speed. Part of the calcium gluconate precipitates and mixes in the filter cake or filter layer, further increasing the density of the filter cake or filter layer, and reducing the product yield. In this regard, the present application adds porous and permeable perlite powder to the crude product material in S7, mixes it into the calcium carbonate, makes the filter cake or filter layer looser, and makes the filtration speed faster; at the same time, the pore size of the perlite powder allows it to intercept macromolecular catalase and glucose oxidase, and allows dissolved gluconate and calcium ions to pass through, so that the filtration effect is better without adding excessive perlite powder; This reduces the loss of calcium gluconate during the purification and separation process, improves product yield, reduces impurities, and improves product purity.

[0016] Optionally, the method further comprises: S8: adding medicinal activated carbon to the crude product filtrate, starting stirring to perform decolorization, and obtaining a clear decolorized liquid after decolorization; S9: The clarified decolorized material is hydraulically filtered to obtain a completely clarified refined filtrate; S10: the refined filtrate is cooled and then pressed into a refined crystallizer, and crystallization is performed by adding seed crystals to obtain a crystal product and a crystal mother liquor; S11: calcium bicarbonate is added to the crystal mother liquor, and crystallization is performed again to precipitate and recover the crystals.

[0017] By adopting the above technical solution, a certain amount of calcium gluconate still remains in the crystallization mother liquor. Calcium bicarbonate is added to increase the calcium ion concentration in the crystallization mother liquor, promote the precipitation of calcium gluconate, increase the product acquisition, and thus improve the product yield.

[0018] Optionally, the seed crystal particle size is 200 μm.

[0019] By adopting the above technical solution, crystallization is faster, the crystals are fine, and the water content inside the crystals is less, so that less soluble impurities are entrained and the purity of calcium gluconate is higher.

[0020] In summary, this application has at least the following beneficial effects: 1. Increase the glucose concentration, use pure oxygen to pass into the oxidation tank, add polyether defoamer to the mixed raw materials, so that the liquid surface in the oxidation tank and the gas phase in the tank can be contacted and replaced quickly, accelerate the oxidation of glucose and improve the oxidation reaction process, so that the reaction process can be close to the theoretical expectation in a shorter time, reduce the production of side reaction products, and thus improve the product yield and purity; 2. The polyether defoamer is first mixed into the mixed raw materials and then evenly dispersed, so that the defoaming effect and anti-foaming effect of the polyether defoamer can be optimized; at the same time, the effective ingredients of catalase and glucose oxidase are polypeptides or proteins, and the polyether defoamer is first mixed into the mixed raw materials to promote the dispersion of catalase and glucose oxidase in the mixed raw materials, thereby accelerating the oxidation of glucose and the reaction process, and the obtained calcium gluconate has better purity and higher yield. DETAILED DESCRIPTION

[0021] raw material: Starch, glucose, calcium carbonate, polyethylene glycol, polypropylene glycol, perlite powder, and medicinal activated carbon are all commercially available products of food grade purity, among which the polyethylene glycol is polyethylene glycol 400 and the polypropylene glycol is polypropylene glycol 600.

[0022] The particle size of calcium carbonate is 5 μm, and the particle size of perlite powder is 20 μm.

[0023] The high temperature amylase is a commercially available high temperature α-amylase from Jiangsu Caiwei Biotechnology Co., Ltd.

[0024] The compound saccharifying enzyme is commercially available from Xingtai Wanda Bioengineering Co., Ltd.

[0025] Catalase and glucose oxidase were purchased from Genencor (China) Bioengineering Co., Ltd. The catalase product name is Multifect CA8000L, and the glucose oxidase product name is GC 199.

[0026] Example 1 A method for preparing calcium gluconate, comprising the following steps: S1: Starch and water are mixed to prepare a starch emulsion with a starch content of 25.4 wt%. After sterilization, high-temperature amylase is added to the starch emulsion, and the amount of high-temperature amylase added is 1.1 wt% of the amount of starch used. The temperature is raised to 105° C. for primary spray liquefaction, and after standing and keeping the temperature for 6 minutes, a secondary spray liquefaction is performed at a temperature of 120° C. to obtain a liquefied starch solution; S2: After cooling the liquefied starch solution to 40°C, a composite saccharifying enzyme is added, wherein the amount of the composite saccharifying enzyme is 1.3wt% of the liquefied starch solution, and the mixture is enzymatically hydrolyzed at 40°C for 30h and then heated to 95°C to inactivate the enzyme, thereby obtaining a glucose saccharified solution; S3: filtering and removing salt using ion exchange resin to obtain purified sugar solution; S4: filtering, concentrating and purifying the sugar solution to obtain a concentrated purified sugar solution having a glucose concentration of 45 wt %; S5: 10.18 kg of concentrated purified sugar solution and 1.26 kg of calcium carbonate are mixed to obtain a mixed raw material, and the mixed raw material is put into an oxidation tank; S6: 0.025 g / L of a polyether defoamer is added to the mixed raw material under stirring, and the polyether defoamer is obtained by compounding polyethylene glycol and polypropylene glycol at a mass ratio of 1:0.65. After mixing evenly, the material in the oxidation tank is heated to 37°C, stirring is turned off, 50 g of catalase and 50 g of glucose oxidase are added, stirring is turned on, and compressed pure oxygen is introduced as reaction oxygen supply, and the compressed pure oxygen flow rate is 0.04 m 3 / h, maintaining the tank pressure at 0.3-0.4MPa for oxidation reaction, and reacting until the residual glucose in the material drops below 0.1wt%, thereby obtaining a crude product material; S7: raising the temperature of the crude product material to 90° C., adding 1 g / L of 20 μm pearlite powder to the crude product material, and then adding calcium carbonate to adjust the pH of the liquid in the crude product material to 7, keeping the temperature for 30 minutes, and then filtering to obtain the crude product filtrate; S8: The crude product filtrate is concentrated under reduced pressure at -0.075 MPa and 70°C to a specific gravity of 1.0850-1.0950. After the concentration is completed, 0.1% (w / v) medicinal activated carbon is added and stirring is started for decolorization. The decolorization time is 60 min. S9: The decolorized material is hydraulically filtered through a filter with a filter layer formed by pearlite powder in advance. The filtrate is required to be completely clarified. The filtrate that does not meet the requirements is circulated back to the filter and re-filtered until it is completely clarified to obtain a refined filtrate; S10: After cooling, the refined filtrate is pressed into a refined crystallizer, and a seed crystal with a particle size of 200 μm is added at a rate of 0.02 g / L, and crystallization is carried out at room temperature for 24 hours. When the crystallization is completed, a crystallized product and a crystallization mother liquor are obtained; S11: placing the crystallized product into a centrifuge for centrifugal separation, rinsing with purified water each time the crystallization is carried out, and the washing is repeated 3 times to obtain a wet product; S12: The wet product is put into a granulator for granulation, and then dried and granulated to obtain the product calcium gluconate.

[0027] Example 2 A method for preparing calcium gluconate, which is different from Example 1 in that the polyether defoaming agent is polyethylene glycol.

[0028] Example 3 A method for preparing calcium gluconate, which is different from Example 1 in that the polyether defoaming agent is polypropylene glycol.

[0029] Comparative Example 1 A method for preparing calcium gluconate, which is different from Example 1 in that no polyether defoaming agent is added in S6.

[0030] Comparative Example 2 A method for preparing calcium gluconate, which differs from Example 1 in that: The glucose concentration in the concentrated purified sugar solution in S4 is 15 wt %; In S5, 10.18 kg of concentrated purified sugar solution and 0.42 kg of calcium carbonate are mixed to obtain a mixed raw material, and the mixed raw material is put into an oxidation tank, that is, the mass of the concentrated purified sugar solution remains unchanged, and the calcium carbonate becomes one third of that in Example 1 as the amount of glucose decreases; No polyether defoamer was added to S6, and compressed air was used as the reaction oxygen supply. The compressed air flow rate was 0.04m 3 / h, maintaining the tank pressure at 0.3-0.4MPa for oxidation reaction.

[0031] Comparative Example 3 A method for preparing calcium gluconate, which differs from Example 1 in that: The glucose concentration in the concentrated purified sugar solution in S4 is 15 wt %; In S5, 10.18 kg of concentrated purified sugar solution and 0.42 kg of calcium carbonate are mixed to obtain a mixed raw material, and the mixed raw material is put into an oxidation tank, that is, the mass of the concentrated purified sugar solution remains unchanged, and the calcium carbonate becomes one third of that in Example 1 as the amount of glucose decreases; S6 uses compressed air as the reaction oxygen supply, and the compressed air flow rate is 0.04m 3 / h, maintaining the tank pressure at 0.3-0.4MPa for oxidation reaction.

[0032] Example 4 A method for preparing calcium gluconate, which is different from Example 1 in that the amount of the polyether defoamer used is 0.01 g / L.

[0033] Example 5 A method for preparing calcium gluconate, which is different from Example 1 in that the amount of the polyether defoamer used is 0.02 g / L.

[0034] Example 6 A method for preparing calcium gluconate, which is different from Example 1 in that the amount of the polyether defoamer used is 0.03 g / L.

[0035] Example 7 A method for preparing calcium gluconate, which is different from Example 1 in that the amount of the polyether defoamer used is 0.04 g / L.

[0036] Example 8 A method for preparing calcium gluconate, which differs from Example 1 in that S6 is different, as follows: 0.025 g / L polyether defoamer, 50 g catalase, and 50 g glucose oxidase were added to the mixed raw materials while stirring. The polyether defoamer was prepared by mixing polyethylene glycol and polypropylene glycol at a mass ratio of 1:0.65. After mixing evenly, the temperature was raised to 37°C, and compressed pure oxygen was introduced. The compressed pure oxygen flow rate was 0.04 m 3 / h, maintaining the tank pressure at 0.3-0.4MPa for staged oxidation reaction, and reacting until the residual glucose content in the material drops below 0.1wt%, thereby obtaining a crude product material.

[0037] Example 9 A method for preparing calcium gluconate, which is different from Example 1 in that no perlite powder is added in step S7, that is, the amount of perlite powder added in S7 is 0.

[0038] Example 10 A method for preparing calcium gluconate, which is different from Example 1 in that the amount of perlite powder used in S7 is 0.2 g / L of crude product material.

[0039] Embodiment 11 A method for preparing calcium gluconate, which is different from Example 1 in that the amount of perlite powder used in S7 is 0.5 g / L of crude product material.

[0040] Example 12 A method for preparing calcium gluconate, which is different from Example 1 in that the amount of perlite powder used in S7 is 1.5 g / L of crude product material.

[0041] Embodiment 13 A method for preparing calcium gluconate, which differs from Example 1 in that the amount of perlite powder used in S7 is 2 g / L of crude product material.

[0042] Embodiment 14 A method for preparing calcium gluconate, which differs from Example 1 in that 42 g / L calcium bicarbonate is added to the crystallization mother liquor obtained in S10, stirred for 30 minutes, filtered to obtain recovered crystals, and the recovered crystals are carried out together with the combined product in subsequent steps.

[0043] Embodiment 15 A method for preparing calcium gluconate, which is different from Example 1 in that the seed crystal particle size used is 100 μm.

[0044] Example 16 A method for preparing calcium gluconate, which is different from Example 1 in that the seed crystal particle size used in S10 is 300 μm.

[0045] Embodiment 17 A method for preparing calcium gluconate, which differs from Example 1 in that the sugar solution is filtered, concentrated and purified in S4 to obtain a concentrated purified sugar solution with a glucose concentration of 40 wt%.

[0046] Product yield, purity detection, oxidation reaction time detection Detect the amount and purity of the products obtained in Examples 1 to 17 and Comparative Examples 1 to 3, and calculate the product yield The results are shown in the following table.

[0047] During the preparation process, the oxidation reaction time in step S6 was recorded, which was the time from the addition of catalase and glucose oxidase to the addition of the mixed raw materials until the residual glucose in the material dropped below 0.1 wt %. The results were recorded in Table 1.

[0048] Table 1. Product purity and yield of Examples 1 to 17 and Comparative Examples 1 to 3 purity / % Product yield / % Oxidation reaction time / h Example 1 98.5 88.5 4 Example 2 98.1 86.6 4.2 Example 3 98.4 88.1 4.3 Comparative Example 1 88.6 76.1 12 Comparative Example 2 85.5 68.9 20 Comparative Example 3 85.7 69.3 20 Example 4 94.1 77 6 Example 5 96.6 82.9 5.5 Example 6 98.4 84.7 4 Example 7 97.7 88.6 4 Example 8 98 86.4 4.3 Example 9 92.2 84.9 4 Example 10 97.1 88.1 4 Embodiment 11 98.3 88 4 Example 12 98.5 88.3 4 Embodiment 13 98.5 88.2 4 Embodiment 14 98.5 92.1 4 Embodiment 15 98.3 88.4 4 Example 16 98 88.5 4 Embodiment 17 98.3 87.8 4.5 Combining Example 1 and Comparative Examples 1 to 3, it can be seen that in Comparative Example 1, a concentrated purified sugar solution with a glucose concentration of 45 wt% was used, pure oxygen was used as the reaction oxygen supply, and no polyether defoaming agent was added, in Comparative Example 2, a concentrated purified sugar solution with a glucose concentration of 15 wt% was used, compressed air was used as the reaction oxygen supply, and no polyether defoaming agent was added, in Comparative Example 3, a concentrated purified sugar solution with a glucose concentration of 15 wt% was used, compressed air was used as the reaction oxygen supply, and a polyether defoaming agent was added, and in Example 1, a concentrated purified sugar solution with a glucose concentration of 45 wt% was used, pure oxygen was used as the reaction oxygen supply, and a polyether defoaming agent was added. In the test results, the product purity of Example 1 was significantly greater than that of Comparative Examples 1 to 3, the product yield of Example 1 was significantly greater than that of Comparative Examples 1 to 3, and the oxidation reaction time of Example 1 was significantly less than that of Comparative Examples 1 to 3.

[0049] In Example 1, the concentration of glucose, the raw material of the oxidation reaction, is increased, and pure oxygen is used as the reaction oxygen supply, and the oxidation reaction rate is increased by the high concentration of the reaction substrate; furthermore, based on the reaction process with high glucose concentration and pure oxygen as the reaction oxygen supply, Example 1 also adds a polyether defoaming agent to the mixed raw materials. For the high-speed reaction with high glucose concentration and pure oxygen as the reaction oxygen supply, the polyether defoaming agent reduces and quickly eliminates the bubbles caused by the gas discharge in the calcium carbonate during the raw material mixing process, the decomposition of hydrogen peroxide during the oxidation process, the release of carbon dioxide by the reaction of calcium carbonate and acid, and the introduction of pure oxygen, so as to avoid the accumulation of bubbles on the liquid surface that hinders the mass transfer interaction between the liquid surface and the gas phase in the tank. Therefore, the high reaction rate of the oxidation reaction with high glucose concentration and pure oxygen as the reaction oxygen supply is actually exerted, so that the oxidation reaction in the oxidation tank maintains a long-term high reaction rate and significantly shortens the reaction time.

[0050] In combination with Example 17, the difference between it and Example 1 is that the glucose concentration in the concentrated purified sugar solution is 40wt%. The product purity and product yield of Example 17 are also significantly better than those of Comparative Examples 1 to 3, and are similar to those of Example 1; the oxidation reaction time of Example 17 is 4.5h, which is similar to 4h of Example 1, and significantly less than that of Comparative Examples 1 to 3.

[0051] Therefore, compared with the traditional oxidation process, the preparation method of the present application has a faster reaction efficiency when using a concentrated purified sugar solution with a glucose concentration of 40 to 45 wt% and pure oxygen as the reaction oxygen supply. The reaction time required to reach the same reaction end sugar concentration can be shortened by 200% to 400% compared with the prior art, and the production of side reaction products is reduced, and the yield and purity of calcium gluconate are improved.

[0052] In combination with Examples 1 to 3, the polyether defoamers used in Examples 1 to 3 are different, wherein the polyether defoamer used in Example 1 is polyethylene glycol and polypropylene glycol compounded in a mass ratio of 1:0.65, and the amount of the polyether defoamer used is 0.025 g / L. The product yield and purity of Example 1 are both higher than those of Examples 2 to 3, and the oxidation reaction time of Example 1 is less than that of Examples 2 to 3. Therefore, it is preferred that the polyether defoamer used in S2 in the preparation process of calcium gluconate in the present application is polyethylene glycol and polypropylene glycol compounded in a mass ratio of 1:0.65.

[0053] The amount of polyether defoamer in S2 also affects the yield and purity of the product. If the amount of polyether defoamer is too little, the defoaming and antifoaming effects are poor, and the yield and purity of the obtained calcium gluconate are low. If the amount of polyether defoamer is too much, the intermediate material in the process contains more polyether defoamer and substances that are soluble in the polyether defoamer, and the purity of the obtained calcium gluconate is low.

[0054] By comparing Example 1 with Examples 4 to 7, it can be seen that the yields of calcium gluconate in Example 4, Example 5, Example 1, Example 6, and Example 7 increase one by one, while the purity of calcium gluconate reaches a peak in Example 1 and Example 6. In Example 7, the amount of polyether defoamer used is higher but the purity of calcium gluconate decreases. The amount of polyether defoamer used in step S1 of the present application is preferably 0.025 g / L.

[0055] By comparing Example 1 and Example 8, it can be seen that the yield and purity of calcium gluconate obtained in Example 8 are lower than those in Example 1. This is because glucose oxidase will begin to contact and oxidize glucose after being added to the mixed raw materials. In Example 1, the polyether defoamer is first mixed into and evenly dispersed into the mixed raw materials, which can optimize the defoaming effect and foam suppression effect of the polyether defoamer; at the same time, the active ingredients of catalase and glucose oxidase are polypeptides or proteins, and the polyether defoamer is first mixed into the mixed raw materials to promote the dispersion of catalase and glucose oxidase in the mixed raw materials, thereby accelerating the oxidation of glucose and the reaction process, and the obtained calcium gluconate has better purity and higher yield.

[0056] Comparing Example 1 and Example 9, since pearlite powder is added to the crude product material in step S7 of Example 1, the filter layer formed by mixing pearlite powder and calcium carbonate when filtering the crude product material in Example 1 has a pore size for the dissolved gluconate and calcium ions to pass through, which has a good filtering effect and a small pressure drop, and a faster filtering speed. At the same time, the macromolecular catalase and glucose oxidase are intercepted, and the loss of calcium gluconate in the purification and separation process is reduced, the product yield is improved, and the mixing of impurities is reduced, and the product purity is improved. Therefore, the yield and purity of calcium gluconate obtained in Example 9 are lower than those in Example 1.

[0057] In combination with Comparative Example 1 and Examples 10 to 13, it can be seen that the amount of pearlite powder added in step S7 of Example 10, Example 11, Example 1, Example 12, and Example 13 increases successively. Between Example 10, Example 11, and Example 1, as the amount of pearlite powder increases, the purity of the product increases, while between Example 1, Example 12, and Example 13, the purity of the product no longer increases; between Example 10, Example 11, and Example 1, as the amount of pearlite powder increases, the product yield increases, while between Example 1, Example 12, and Example 13, the product yield no longer increases and shows a downward trend as the amount increases, so it is better for the present application to add pearlite powder to the slurry in step S2 in an amount of 0.50 to 1.50 g / L.

[0058] By comparing Example 1 and Example 14, it can be seen that a certain amount of calcium gluconate still remains in the crystallization mother liquor. In Example 14, calcium bicarbonate is added to the crystallization mother liquor obtained from S5 to increase the calcium ion concentration in the crystallization mother liquor, promote the precipitation of calcium gluconate, increase the product acquisition, and thereby improve the product yield.

[0059] Different particle sizes of added seed crystals will affect the crystallization precipitation rate and precipitation distribution, and further affect the amount of solution entrained in the crystals, thereby affecting the product purity; by comparing Example 1, Example 15 and Example 16, it can be seen that the product purity of Example 1 is the highest, so the seed crystal particle size used in this application is preferably 200μm.

[0060] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. After reading this specification, those skilled in the art can make non-creative modifications to this embodiment as needed, but as long as it is within the scope of protection required by the present invention, it will be protected by the patent law.

Claims

1. A method for preparing calcium gluconate, characterized in that, The following steps are included: S1: Starch and water are mixed to prepare starch emulsion, high temperature amylase is added to the starch emulsion after sterilization, and after heating, primary injection liquefaction and secondary injection liquefaction are performed in sequence to obtain liquefied starch liquid; S2: After the liquefied starch solution is cooled, a composite saccharifying enzyme is added to obtain a glucose saccharified solution after enzymolysis and inactivation; S3: filtering and removing salt using ion exchange resin to obtain purified sugar solution; S4: filtering, concentrating and purifying the sugar solution to obtain a concentrated purified sugar solution with a glucose concentration of 40-45 wt %; S5: stirring and mixing the concentrated purified sugar solution and calcium carbonate to obtain a mixed raw material, and putting the mixed raw material into an oxidation tank; S6: Add polyether defoamer, catalase and glucose oxidase to the mixed raw materials and heat to 35-38°C, stir and introduce pure oxygen, maintain the tank pressure at 0.3-04Mpa for oxidation reaction, detect the glucose content during the oxidation reaction, and terminate the reaction when the residual glucose drops below 0.1wt% to obtain a crude product material; the polyether defoamer is used in an amount of 0.02-0.03g / L of mixed raw materials.

2. A method for preparing calcium gluconate according to claim 1, characterized in that, The polyether defoamer is one or both of polyethylene glycol and polypropylene glycol.

3. A method for preparing calcium gluconate according to claim 2, characterized in that, The polyether defoamer is prepared by mixing polyethylene glycol and polypropylene glycol in a mass ratio of 1:0.65, and the dosage of the polyether defoamer is 0.025 g / L.

4. A method for preparing calcium gluconate according to claim 1, characterized in that, First, a polyether defoamer is added to the mixed raw materials in S6, and then the temperature is raised to 35-38° C., and then catalase and glucose oxidase are added. The oxidation reaction time is 4-6 hours.

5. A method for preparing calcium gluconate according to claim 1, characterized in that, The method further comprises: S7: heating the crude product material, adding calcium carbonate to adjust the pH value of the liquid to 6.5-7.5, adding perlite powder, and filtering to obtain a crude product filtrate; the amount of perlite powder added in S7 is 0.50-1.50 g / L of the crude product material.

6. A method for preparing calcium gluconate according to claim 5, characterized in that, Also includes, S8: Add medicinal activated carbon to the crude product filtrate, start stirring to perform decolorization, and obtain a clear decolorized liquid after decolorization; S9: The clarified decolorized material is hydraulically filtered to obtain a completely clarified refined filtrate; S10: After cooling, the refined filtrate is pressed into a refined crystallizer, and crystallization is performed by adding seed crystals to obtain a crystal product and a crystal mother liquor; S11: adding calcium bicarbonate to the crystallization mother liquor, and crystallizing and precipitating again to recover the crystals.

7. A method for preparing calcium gluconate according to claim 5, characterized in that, The seed particle size is 200 μm.

Images